The present invention relates generally to devices for controlling the opening and closing of fluidtight doors in contact with different pressures on its opposite sides.
The invention will be described more particularly for use for controlling autoclave doors, but it will be understood that the device according to the invention may be used with any chamber which is subjected to an internal or external pressure which may or may not be high and equipped with an access opening closed by a door which hermetically withstands internal or external pressures when the chamber is in operation, and more specially to any door, air lock or the like, between two zones subjected to different pressures wherein excellent fluidtightness must be provided.
In the field of autoclaves various systems for closing doors are known.
In one of these systems a series of levers are disposed substantially radially on the outer side of the door (which in general is of circular contour). The radially outer ends of the levers are displaceable radially of the door and perpendicular to the plane thereof in order to bear against a collar fixed to the frame of the autoclave surrounding the access opening and adapted to lock the door of the autoclave in its closed fluidtight position.
The other ends of the levers are controlled simultaneously by a movable annular member by means of a handwheel, both in rotation and translation perpendicular to the plane of the door.
This system is complicated and expensive to make because the levers and the control device must be precision machined owing to the movements of the levers in three dimensions if perfect fluidtightness and high pressure resistance are desired, which means the bearing ends of all the levers being displaced strictly synchronously and simultaneously bearing on the locking collar.
Further, this system may be dangerous in case of accidental opening of the door since once the levers free themselves from the locking collar nothing retains the door, which may open violently under internal pressure causing accidents.
In a second known system lateral translation of the door is employed. The door in its closed position is held captive in slides fixed to the frame of the autoclave and urged against these slides by means of an inflatable seal housed in a groove formed around the access opening. This system is even more complex than the preceeding one since it requires pressurized fluid supply in the groove in which the inflatable seal is housed and utilizes a complete control system for operating this seal in the course of opening and closing the door.
Such a device is therefore expensive. It is also delicate and less reliable than the preceeding one. Further the seal employed is a special expensive seal and it must be replaced regularly as it wears and may be deformed or damaged in the course of inflation and deflation in the housing in order to bear flush against the door (when closed) and to retract or collapse in the groove (when open).